1. Field of the Invention
The present invention relates generally to separating components of mixtures. More specifically, but not by way of limitation, the present invention relates to pressure-driven devices for moving molecules of at least one component against a concentration gradient to separate the at least one component from a mixture.
2. Discussion of Related Art
Separating mixtures efficiently and cost-effectively has long been an object of the prior art. More specifically, it is often desirable to separate one or more components out of a mixture containing several components. This applies especially to mixtures containing components having similar properties, and/or mixtures having a solid dissolved or otherwise dispersed within a liquid on a small scale that are often the most difficult or costly mixtures to separate. For example, a mixture of two liquids having similar boiling points can be especially expensive to separate by traditional means, such as distillation. Additionally, mixtures having a solid dissolved or otherwise dispersed in a liquid on a small scale can be especially difficult to separate by traditional means, such as screening and or filtration.
Numerous examples of such mixtures are well known in the art, such as, but not limited to, saltwater/seawater, petroleum and/or hydrocarbon mixtures, alcohol/water, propane/propylene, propanol/isopropanol, o-xylene/m-xylene, enantiomers, racemic mixtures, and/or nearly any other mixtures. Saltwater especially is a mixture for which it is highly desirable to separate into its major components, water and salts, as well as minor components, such as contaminants. The demand for efficient and effective separation or desalinization of saltwater is ever increasing, especially as the earth's population increases and traditional freshwater sources become contaminated with pollutants.
In the prior art, numerous attempts have been made, and numerous methods researched, for such difficult and/or desirable separations of mixtures. Some examples of such attempts and/or methods can be found in the following U.S. patent references: U.S. Pat. No. 4,339,247 (issued to Faulkner et al.); U.S. Pat. No. 4,673,512 (Schram); U.S. Pat. No. 5,147,562 (Heyman); U.S. Pat. No. 5,951,456 (Scott); U.S. Pat. No. 6,210,470 (Phillips et al.); U.S. Application Publication No. 2003/0192427 (Geller et al.); U.S. Application Publication No. 2006/0027487 (Matsuura); Statutory Invention Registration H1,568 (Huang et al.), all of which are incorporated herein by reference in their entirety. Additional examples may also be found in the following non-patent references: Mandralis, Z. I. and Feke, D. L., Continuous suspension fractionation using acoustic and divided-flow fields, Chemical Engineering Science (1993), 48(23), 3897-905; Mukhopadhyay, R., Research Profiles: Continuous separations by acoustic forces, Analytical Chemistry (2007), 79(15), 5504; Muralidhara, H. S. and Ensminger, D., Acoustic dewatering and drying: state of the art review, Proceeding to the 4th International Drying Symposium, (1984), 1, 304-15; Nii, S., Matsuura, K., Fukazu, T., Toki, M., and Kawaizumi, F., A novel method to separate organic compounds through ultrasonic atomization, Chemical Engineering Research and Design (2006), 84(A5), 412-415; Sato, M., Matsuura, K., and Fujii, T., Ethanol separation from ethanol-water solution by ultrasonic atomization and its proposed mechanism based on parametric decay instability of capillary wave, Journal of Chemical Physics (2001), 114(5), 2382-2386; Semyonov, S. N. and Maslow, K. I., Acoustic field-flow fractionation, Journal of Chromatography (1988), 446, 151-6; Spoor, P. S. and Swift, G. W., Thermoacoustic Separation of a He—Ar Mixture, Physical Review Letters (2000), 85(8), 1646-1649; Srinivas, N. D., Barhate, R. S., Raghavarao, K. S. M. S., and Todd, P., Acoustic demixing of aqueous two-phase systems, Applied Microbiology and Biotechnology (2000), 53(6), 650-654; Tolt, T. L. and Feke, D. L., Analysis and application of acoustics to suspension processing, Proceedings of the 23rd Intersociety Energy Conversion Engineering Conference (1988), 4, 327-31; Tolt, T. L. and Feke, D. L., Separation of dispersed phases from liquids in acoustically driven chambers, Chemical Engineering Science (1993), 48(3), 527-40.
Thermoacoustic engines and heat pumps have been developed to transport thermal energy against a temperature gradient. In general, such devices provide one or more plates disposed within a tube or channel. The plate(s) are provided with a low-temperature thermal sink at one end and a high-temperature thermal source at the other end so as to create and maintain a thermal gradient along the length of the plates. An acoustic source activated to provide standing (and in some cases traveling) acoustic waves along the length of the plates to cause pressure oscillations in the gas and/or other fluid along the length of the plates. Such pressure oscillations create spatial and volumetric oscillations in the fluid along the length of the plates as well. The oscillating field of pressure induces an oscillating velocity field. Because the fluid is compressible, the oscillations cause the fluid along the length of the plate to absorb thermal energy from the relatively colder end of the plate and transport the thermal energy towards the relatively hotter end of the plate, against the temperature gradient.
As will also be appreciated by those skilled in the art, the vast majority of heat transfer occurs within or near the boundary layer of the fluid along the plate. Additionally, the oscillations in pressure, and thereby temperature and volume, are limited by the power of the acoustic waves supplied, and thus higher capacity for thermal transport against the gradient may, in some cases, be more easily achieved by increasing the surface area of the plate or plates available for the transfer and transport of thermal energy.
A more detailed description of such thermoacoustic devices, as well as illustrative figures, may be had by reference to “Thermoacoustic engines” by G. W. Swift, in the Journal of the Acoustical Society of America, Volume 84, Pages 1145-1180, October 1988 (J. Acoust. Soc. Am. 84(4), October 1988), the entire content of which is hereby incorporated herein by reference.
All patents, published patent applications, and published articles and references listed herein are hereby expressly incorporated by reference in their respective entireties.